Consumers expect the food industry to provide safe products that comply with the latest legislations. The Association of the European Adhesive and Sealant Industry (FEICA) already recommends avoiding the use of epoxy silanes in food contact applications, and the EU is expected to set new limits during the course of this year. These limits will require complex testing methods, and will inevitably lead to challenges for converters and packaging manufacturers.
Thanks to Henkel’s long-standing experience in food safe packaging, the company has been able to develop a new range of laminating adhesives that are free of epoxy silanes, and a new test method that requires a combination of several sophisticated analytical techniques to detect epoxy silanes and its degradation products.
Epoxy silanes, like GLYMO and GLYEO, are adhesion-promoters used in food packaging – laminated pouches, for example, which must be resistant to sterilisation and hot filling. In some cases, it is also used for microwaveable packaging. These adhesion-promoters have very favourable attributes, which is why they can be found in a variety of applications. They increase the adhesion between aluminium and polyolefin films, and maintain the bond strength even at elevated temperatures.
Because GLYMO is used in a wide variety of food contact applications, the European Food Safety Authority (EFSA) had a closer look at existing toxicological data. In 2017, EFSA concluded that GLYMO must be considered to have a genotoxic potential. “Therefore,” says Dr Monika Töennießen, Henkel’s head of food safety compliance – global food safety, product safety and regulatory affairs, “the EU is now working on a legislative framework for 2020 to regulate the use of epoxy silanes, according to their genotoxic potential. The deadline is envisaged for September 2020. This will raise demand for suitable alternatives.”
FEICA already recommends replacing the adhesion-promoter as soon as possible. In the near future, the application of GLYMO as an adhesion promoter will still be permitted as long as it can be demonstrated that it does not endanger human health. Products containing epoxy silane are not permitted to be used for fatty filling goods, and epoxy silanes must not be detectable in aqueous filling goods.
“The critical part,” explains Dr André Weiss, manager of instrumental analytics, project management food safety, “will be that converters and packaging manufacturers need to provide proof for the absence of GLYMO and structurally similar chemicals, such as GLYEO. This implies two factors: having the right epoxy silane-free adhesive or the right testing method to prove that no epoxy silane is migrating. Henkel Corporate Analytics has developed a unique approach for the determination of GLYMO and GLYEO derivates, which is leading within the market. The testing, however, will create additional workload and administrative paperwork for the converter’s quality control departments.”
As a leading adhesive manufacturer, Henkel anticipated this development early on, and started to work on epoxy silanefree adhesives. These systems, which are specifically designed for high-temperature food contact and medical retort applications, are modular in their design. The adhesive base Loctite Liofol LA 2798 can be combined with a variety of hardeners, making it versatile and complexity-reducing for converters. Henkel currently offers four hardeners, each with different features, to cover a broad range of applications.
For dried animal food or hot filling goods, Henkel provides two aromatic hardeners for boiling and pasteurisation. These mediumhigh performance systems can be cured at room temperature, and are designed for high-temperature resistance and high heatsealing strength. For high performance, Henkel offers an aliphatic hardener for general retort, which cures at room temperature and is recommended for 45-minute sterilisation processes at 134°C. This makes it the ideal high-performance adhesive for baby foods, for example. For the packaging and sterilising of liquid, in particular, aggressive filling goods such as fatty foods and oily fatty contents, such as cat food, Henkel recommends another hardener combination. This system is designed for processing temperatures of 134°C for 45 minutes, and its modularity enables customers to reduce complexity while providing flexibility.
The adhesion properties and performance of these GLYMO- and GLYEO-free adhesive systems have already been confirmed during industrial use by several of its customers. The products are commercially available, and offer an effective opportunity to be on the safe side of the epoxy silane discussion.